1. Field of the Invention
The present invention relates to a mobile cleaning device for remotely removing and collecting high radioactive waste debris in a highly radioactive environment of hot-cell for treating and fabricating high radioactive material of spent nuclear fuel, which direct human access to the in-cell is limited to the strictest minimum and is sometimes even impossible. The device operated by remote control moves to the desired cleanup location removes, sucks, and collects loose dry spent nuclear fuel powder and other high radioactive waste debris adhered to both the contaminated in-cell floor and various spent nuclear fuel process and fabrication equipment without spreading inside the hot-cell, thereby maintaining the desired soundness of the hot-cell facility and improving workers"" safety by completely eliminating workers"" exposure to high-radioactive contaminants.
2. Description of the Prior Art
Known well to those skilled in the art the treatment and fabrication of high radioactive materials such as spent nuclear fuel requires to be carried out inside a completely shielded hot-cell. As the hot-cell is active, workers can""t access the in-cell because of the nature of the high radioactivity of spent nuclear fuel. Even personnel in specified radiological turnouts are allowed limited access to the in-cell only when its radiation level is below an allowable one. Undesirable products such as spent nuclear fuel powder debris and contaminated wastes are inevitably created during the spent nuclear fuel treatment and fabrication processes. These products are deposited on both the in-cell floor and the surface of various process equipment located inside the hot-cell, thus contaminating the hot-cell steady. Such radioactive waste needs to be cleaned periodically to prevent the contamination from spreading inside the hot-cell.
In the prior art the removal and collection of radioactive waste debris from both the in-cell floor and the surfaces of the equipment are accomplished by using a conventional vacuum cleaner. However; such a conventional vacuum cleaner to be used in a hot-cell has several problems of remote control, maintenance, and repair. The materials and components of the conventional vacuum cleaner inside the hot-cell are apt to be easily damaged because of the high radioactivity of spent nuclear fuel. It is not easy for the vacuum cleaner to effectively remove and clean the radioactive waste firmly adhered to the in-cell floor or to be moved to a desired cleaning position either by a crane or a remote manipulator installed inside the hot cell. Even possible, it takes much time to transfer the vacuum cleaner to a desired cleaning target. The performance and efficiency of the conventional vacuum cleaner are also reduced due to its limited workspace inside the hot-cell. The storage bag of such a vacuum cleaner undesirably leaks the collected fine radioactive waste into the in-cell atmosphere, thus further spreading the contamination over the in-cell. In addition, it is very difficult to remotely replace a storage bag of the cleaner with a new one or to remotely treat and dispose the collection bag by maneuvering a manipulator or other appropriate tools in situ. Direct exchange of the used bag for a new one by a worker in a specified radiological turnout inside the hot-cell may not be possible to complete the task within a predetermined limited time and may thus cause to expose the worker to excessive radiation, thereby resulting in severe safety problems.
In case of which the conventional vacuum cleaner located inside the hot-cell is damaged or broken, it is not possible to repair or exchange it by a remote means. Therefore, the damaged or broken vacuum cleaner is kept within the hot cell. This undesirably increases the amount of the in-cell radioactive waste, proliferates the contamination level of the hot-cell, increases the cost of radioactive waste treatment and disposal, and degrades the operational function of the hot-cell. In addition, the spent nuclear fuel or special nuclear material requires to be measured in its quantity before and after specified processes inside the hot-cell for nuclear material control and accounting, so that its lost quantity during the processes is evidently identified. Such loss measurement, however, can""t be accomplished accurately because the conventional vacuum cleaner can""t effectively collect the radioactive waste inside the hot-cell.
The present invention has been made to solve the above-described problems occurring in the prior art, an object of the invention is to provide a remote-controlled mobile cleaning device, which will be employed in a hazardous environment to which direct human access is impossible.
Another object of the invention is to provide a remote-controlled mobile cleaning device capable of remotely cleaning the hot-cell floor and in-cell process and fabrication equipment contaminated with radioactive materials in a highly radioactive environment of hot-cell in which spent nuclear fuel is handled and fabricated, while completely eliminating worker""s exposure to high-radioactive contaminants.
Still another object of the invention is to provide a remote-controlled mobile cleaning device capable of remotely collecting loose dry spent nuclear fuel debris and other radioactive waste without proliferating the contamination level of the in-cell, thereby maintaining a desired soundness of the hot-cell facility.
In order to accomplish the above object, the present invention provides a remote-controlled mobile cleaning device for the collection of high-radioactive waste debris in hot-cell comprising: a navigation means for climbing over such obstacles as electrical cables and pneumatic tubes placed on the hot-cell floor, suction and collections means for dislodging, filtering, and capturing high radioactive waste debris, and cover means for protecting suction and collection means. The device that is operated by remote control moves to a desired cleanup and collection position, cleans, and collects loose dry spent nuclear fuel debris and other high-radioactive waste adhered to contaminated in-cell floor or process and fabrication equipment, without spreading contaminants inside the hot-cell.